JP3967436B2 - Regenerative repeater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a regenerative repeater that regenerates and relays a radio signal, and more particularly to an improvement of a regenerative repeater that employs a local wraparound interference cancellation method.
[0002]
[Prior art]
When a regenerative repeater that generates and transmits a radio reproduction signal having the same frequency as a radio reception signal is used in an open space, it is necessary to sufficiently consider the physical arrangement relationship between the transmission antenna and the reception antenna.
In particular, when the distance between the antennas is short, if the coupling between the two antennas increases, a failure such as oscillation may occur, and normal relay service may not be possible. This is because the ratio of the level at which the output of the regenerative repeater wraps around and enters the receiving antenna and the level of the radio signal from the base station, which is originally intended for relaying, is such that the demodulator of this repeater can operate normally. Occurs when falling below the / U ratio.
[0003]
In order to solve this problem, conventionally, a technique for reducing the coupling between antennas by devising the directivity of the transmitting antenna and the receiving antenna, and a local wraparound interference elimination method are known.
[0004]
A regenerative repeater employing the local station wraparound interference cancellation method will be described below.
FIG. 6 is a block diagram showing a regenerative repeater employing the local station wraparound interference cancellation method.
In the regenerative repeater 1 shown in FIG. 6, reference numeral 10 denotes a regenerative repeater circuit. Reference numeral 11 denotes a receiving antenna. The receiving antenna 11 is originally an antenna for the regenerative repeater 1 to receive a radio wave (desired signal) intended for relaying. Reference numeral 12 denotes a receiving circuit whose input side is connected to the receiving antenna 11 and outputs the received signal with the output of the receiving antenna 11 as an input.
[0005]
In the regenerative repeater 1, reference numeral 13 is connected to the output side of the receiving circuit 12, and is also connected to the output side of a cancel signal adjusting circuit, which will be described later, and the received signal from the receiving circuit 12 and the cancel signal adjusting circuit This is an adder circuit that adds and outputs a cancel signal. Reference numeral 14 is connected to the output side of the adder circuit 13 and demodulates the output of the adder circuit 13 as input. Reference numeral 15 is connected to the output side of the demodulator circuit 14 and remodulates the demodulated signal of the demodulator circuit 14. This is a modulation circuit to be performed.
[0006]
Further, in the regenerative repeater 1, reference numeral 16 is connected to the output side of the modulation circuit 15, and a transmission circuit that generates and outputs a radio output signal from the modulation signal output from the modulation circuit 15, and 17 is an output side of the transmission circuit 16 Is connected to the transmitting antenna that radiates radio waves as a relay output, and 18 is connected to the output side of the modulation circuit 15 to adjust the phase, amplitude, and delay of the output of the modulation circuit 15, and within the output signal of the receiving circuit 12. A cancel signal adjustment circuit that generates an antiphase signal having the same amplitude and delay time as the wraparound signal component included in the signal and outputs the generated signal as a wraparound signal cancel signal for canceling the wraparound signal. is there.
[0007]
As shown by such a configuration, in the conventional regenerative repeater 1, the replica of the wraparound component is subtracted from the received signal which is a composite signal of the desired signal and the wraparound signal component from the transmission antenna. The desired signal is extracted by removing the noise component. Then, the desired signal is passed to the demodulating circuit 14 at the subsequent stage to perform normal demodulation and remodulation.
[0008]
[Problems to be solved by the invention]
However, in the conventional technology, there is a problem that a technique for reducing the coupling between the antennas by devising the directivity of the transmission antenna and the reception antenna may not match the directivity corresponding to the area where the relay service is desired. In addition, there is a limit to the amount of coupling reduction between the transmitting and receiving antennas, and there is also a problem that the cost of the antenna is greatly increased.
[0009]
On the other hand, in the technique using the local wraparound interference cancellation method shown in FIG. 6, since the wrap signal component is positively canceled in the local station, it is effective, but the output signal of the actual subtraction result is A slight error between the wraparound component and the wraparound cancel signal is included as a residual error.
This residual error is caused by waveform distortion or delay error given by band limitation in the transmission path (especially the channel filter). In the vicinity of the wraparound component and the change point of the modulation symbol of the wraparound cancel signal synchronized therewith, The amount of error is significantly increased. This residual error may cause a significant obstacle to the demodulation operation in the regenerative repeater.
[0010]
FIG. 7 is a time chart showing the timing of each signal of the conventional apparatus shown in FIG. 6 for illustrating a case where the above-described residual error causes a large obstacle to the demodulation operation in the regenerative repeater.
In each of FIGS. 7A to 7E, the horizontal axis represents a common time axis.
(A) and (B) of FIG. 7 show the wraparound component of the received signal and the change timing (X mark) of the modulation symbol in the cancel signal, respectively. Since the change timings of the modulation symbols (A) and (B) are adjusted to be substantially the same by the cancel signal adjustment circuit 18, they are shown at almost the same timing on the time axis.
[0011]
(C) represents the signal after cancellation, that is, the output signal of the adder circuit 13. This indicates that the error (cancellation residual) component is large in the vicinity of the data change timing. This is due to the waveform distortion and delay error described above.
[0012]
(D) shows the change timing of the modulation symbol of the desired signal in the received signal. The relationship between the change timing of (A) (this is equal to the change timing of (B) and (C)) and the change timing of (D) is considered to match because the delay time by each circuit element in the device is taken into account. Is not limited (usually does not match). FIG. 7 illustrates a case where there is a ½ hour length shift of the symbol timing.
[0013]
The signal input to the actual demodulation circuit is the sum of the signals indicated by (C) and (D), and the timing of the change is indicated by (E). (E) shows the timing of change of (C) and (D) in the same figure (this is where the error of (C) is large), but overlaps the portion where the symbol of the original desired signal (D) is stable. It shows that.
Therefore, if this error component is large, there is a problem that the desired signal cannot be demodulated normally due to the influence of the component on the demodulation operation.
[0014]
The present invention has been made to solve such a problem, and normal demodulation can be performed by preventing a portion where an error component after cancellation and a portion where a symbol of a desired signal is stable from overlapping. Therefore, an object of the present invention is to obtain a regenerative repeater that can perform normal and stable regenerative relay.
[0015]
[Means for Solving the Problems]
To solve the problems described above, the present invention is, for example, as shown in FIG. 1, 3 to 5, a receiving antenna 11 for receiving radio waves for the purpose of relaying, the output signal of the receiving antenna 11 is input Receiving circuit 12, a demodulating circuit 14 for demodulating a desired reception signal output from the receiving circuit 12, a modulating circuit 15 for modulating a demodulated signal output from the demodulating circuit 14, and the modulating circuit 15 The transmission circuit 16 that transmits the modulation signal output by the reception antenna 11 at the same frequency as the reception signal of the reception antenna 11, the transmission antenna 17 that transmits the output signal of the transmission circuit 16 as a radio wave, and the phase and amplitude of the modulation signal and to adjust the delay, exits the wraparound cancel signal for canceling the transmission signal from the transmitting antenna 17, which is received by the receiving antenna 11 Cancel signal adjustment circuit 18 that performs the above operation, and the reception cancel signal that is demodulated by the demodulation circuit 14 by adding the wraparound cancel signal that is output by the cancellation signal adjustment circuit 18 to the reception signal that is output by the reception circuit 12. An adder circuit 13 to be formed, and delay circuits 20A to 20D for delaying the timing of the modulation symbols of the desired reception signal so that the timing phases of the modulation symbols of the desired reception signal and the wraparound cancellation signal are the same. It will be.
[0016]
According to such a configuration, the timing of the reception desired signal or the modulation symbol can be delayed so that the timing phase of the modulation symbol of the reception desired signal and the wraparound cancellation signal is the same. It is possible to overlap the part where the error component after cancellation of the sneak signal and the part where the symbol of the desired signal is not stable, that is, the part where the error component after the cancellation of the sneak signal occurs and the symbol of the desired signal Since stable parts can be prevented from overlapping, normal demodulation can be performed, and normal and stable regenerative relaying can be performed.
[0017]
In the present invention, the delay circuit includes a low-pass filter or a band-pass filter having a predetermined delay time.
[0018]
Furthermore, in the present invention, the delay circuit 20A is provided on the output side of the modulation circuit 15 as shown in FIG.
[0019]
In the present invention, the modulation circuit 15 is constituted by a digital circuit, and the delay circuit 20A is constituted by a shift register for delaying a modulation signal expressed by a digital numerical value output from the modulation circuit.
[0020]
In the present invention, the delay circuit 20B is constituted by a digital circuit as shown in FIG. 3, and is provided on the output side of the demodulation circuit.
[0021]
According to such a configuration, the signal can be delayed by the delay circuit 20B while maintaining the digital output signal form of the demodulation circuit 14, and the handling of the signal becomes easy.
[0022]
In the present invention, the delay circuit delays the timing of the modulation symbol of the desired signal to be received, and the desired signal appears by a complex correlation operation between the received signal including the desired wave and the undesired wave and the transmission signal. It is set from the time difference between two peaks corresponding to each of the wave and the undesired wave.
[0023]
Further, in the present invention, the delay circuit 20D is provided on a clock supply line, which is an output line of the symbol timing generation circuit 19, which supplies the modulation circuit 15 with a clock for generating a modulation signal. The modulation signal is delayed by delaying.
[0024]
According to such a configuration, the modulation symbol timing can be made variable within one symbol, so that delay control can be easily performed.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a regenerative repeater according to the first embodiment.
In the regenerative repeater circuit 10A of the regenerative repeater 1A shown in FIG. 1, the same reference numerals as those in FIG. 6 denote the same or equivalent objects as shown in FIG. 6, and description thereof is omitted here.
In the figure, 20A is a delay circuit provided between the output side of the modulation circuit 15 and the input side of the transmission circuit 16, and the output side of the delay circuit 20A is connected to the input side of the cancel signal adjustment circuit 18.
[0026]
The delay circuit 20A delays the change timing of the modulation symbol of the desired signal output from the modulation circuit 15, so that the change timing of the modulation symbol in the residual error does not overlap with the portion where the symbol of the desired signal is stable. In other words, the delay circuit 20A is configured to synchronize the change timing of the modulation symbol in the residual error with the same timing as the portion where the symbol of the desired signal is not stable.
[0027]
The operation of the first embodiment will be described below.
FIG. 2 is a flowchart showing the timing of each part of the regenerative repeater circuit 1A shown in FIG.
In each of FIGS. 2A to 2F, the horizontal axis represents a common time axis.
2A and 2B respectively show the wraparound component of the received signal and the modulation symbol change timing (X mark) in the cancel signal. Since the change timings of the modulation symbols (a) and (b) are adjusted to be substantially the same by the cancel signal adjustment circuit 18, they are shown at almost the same timing on the time axis.
[0028]
(C) represents the signal after cancellation, that is, the output signal of the adder circuit 13. This indicates that the error (cancellation residual) component is large in the vicinity of the data change timing. This is due to the waveform distortion and delay error described above.
[0029]
(D) shows the change timing of the modulation symbol of the desired signal in the received signal. The relationship between the change timing of (a) (which is equal to the change timing of (b) and (c)) and the change timing of (d) coincide with each other by adjusting the delay time of the delay circuit 20A.
[0030]
The signal input to the actual demodulation circuit is the sum of the signals shown in (c) and (d), and the timing of the change is shown in (e). (E) is the change timing of (c) and (d) in FIG. 6 (this is where the error of (c) is large) overlaps with the change timing of the original desired signal (d). It shows that the modulation symbol is out of the stable interval.
[0031]
Therefore, the delay provided on the output side of the modulation circuit 15 is performed so that the demodulation operation is performed in this stable interval, and the interval in which the error component near the change point of the modulation symbol of the desired signal is large is not subject to demodulation. The desired signal can be accurately demodulated by adjusting the delay time of the circuit 20A.
[0032]
An example of timing of integrated discharge in demodulation is shown in (f). Note that (f) shows an integral discharge operation of a binary modulation symbol as an example. As shown in the figure, since the triangular integrated discharge pattern avoids a section in which the error component in the signal (e) before demodulation is large, there is no influence on the demodulation result.
[0033]
The delay circuit 20A can be configured by, for example, a low-pass filter or a band-pass filter having a predetermined delay time. Further, when the modulation circuit 15 is configured by a digital circuit, the modulation signal expressed by a digital numerical value output from the modulation circuit 15 can be delayed using a digital circuit such as a shift register or a latch.
[0034]
Note that the delay time is determined by experimentally determining the time difference between the portion (timing) in which the error component after the wraparound signal is canceled in the regenerative repeater circuit and the symbol change point of the desired signal. Alternatively, the time difference may be obtained during relay, and the delay time may be automatically adjusted according to the obtained time difference. This is because, for example, two peaks appear at the timing of the D wave and the timing of the U wave by performing a correlation operation (I / Q complex correlation) between the received wave including the D wave and the U wave and the transmission wave. The delay time of the delay circuit can be set from the difference between the peaks.
[0035]
Embodiment 2. FIG.
FIG. 3 shows the regenerative repeater according to the second embodiment.
In the regenerative repeater circuit 10B of the regenerative repeater 1B shown in FIG. 3, the same reference numerals as those in FIG. 6 denote the same or equivalent objects as shown in FIG. 6, and description thereof is omitted here.
The second embodiment is different from the first embodiment in that the delay circuit 20B is provided between the output side of the demodulation circuit 14 and the input side of the modulation circuit 15.
Even in such a configuration, the same operation as in the first embodiment is performed, and it is obvious that the same operation and effect as in the first embodiment can be obtained.
In this case, since the delay circuit 20B is provided immediately after the demodulation circuit 14, the delay circuit 20B can be easily configured by a digital circuit.
[0036]
Embodiment 3 FIG.
FIG. 4 is a diagram showing a regenerative repeater according to the third embodiment.
In the regenerative repeater circuit 10C of the regenerative repeater 1C shown in FIG. 4, the same reference numerals as those in FIG. 6 indicate the same or equivalent objects as shown in FIG. 6, and description thereof is omitted here.
In the third embodiment, the delay circuit 20C is provided between the output side of the adder circuit 13 and the output side of the demodulator circuit 14.
Even in such a configuration, the same operation as in the first embodiment is performed, and it is obvious that the same operation and effect as in the first embodiment can be obtained.
[0037]
Embodiment 4 FIG.
FIG. 5 shows a regenerative repeater according to the fourth embodiment.
In the regenerative repeater circuit 10D of the regenerative repeater 1D shown in FIG. 5, the same reference numerals as those in FIG. 6 indicate the same or equivalent objects as shown in FIG. 6, and description thereof is omitted here.
In the fourth embodiment, the delay circuit 20D is provided between the output side of the symbol timing generation circuit 19 and the clock input terminal of the modulation circuit 15 for generating a modulation signal.
The symbol timing generation circuit 19 is a circuit that supplies a modulation signal generation clock (symbol timing) to the modulation circuit 15.
[0038]
According to such a configuration, since the timing of the modulation symbol can be made variable within one symbol, delay control within one symbol can be easily realized. As is clear from the time chart of FIG. 2, it is sufficient that the delay control amount of the required timing can be adjusted by a maximum of 0.5 symbols (one symbol in total) forward or backward in time. The configuration of 4 is effective.
[0039]
【The invention's effect】
As described in detail above, according to the present invention, in the regenerative repeater, by providing the delay circuit, the portion where the error component after cancellation and the portion where the symbol of the desired signal is stable do not overlap. Therefore, even if a cancellation residual error occurs due to frequency characteristics and delay errors between the loop propagation path and the loop of the loop cancellation signal, it becomes possible to accurately demodulate the desired signal, and normal regenerative relay service is provided. There is an effect that it can be performed. Since the present invention can be configured only by newly providing a delay circuit in the conventional regenerative repeater, it does not cause any trouble in downsizing and cost reduction of the device.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a regenerative repeater according to Embodiment 1 of the present invention.
FIG. 2 is a time chart showing the operation of the embodiment of the present invention.
FIG. 3 is a block diagram showing a regenerative repeater according to Embodiment 2 of the present invention.
FIG. 4 is a block diagram showing a regenerative repeater according to Embodiment 3 of the present invention.
FIG. 5 is a block diagram showing a regenerative repeater according to Embodiment 4 of the present invention.
FIG. 6 is a block diagram showing a conventional regenerative repeater.
FIG. 7 is a time chart showing the operation of a conventional regenerative repeater.
[Explanation of symbols]
1A, 1B, 1C, 1D Regenerative repeater 10A, 10B, 10C, 10D Regenerative repeater circuit 11 Transmitting antenna 12 Receiving circuit 13 Adder 14 Demodulating circuit 15 Modulating circuit 16 Transmitting circuit 17 Transmitting antenna 18 Cancel signal adjusting circuits 20A, 20B, 20C, 20D delay circuit

Claims (7)

A receiving antenna for receiving radio waves for relay purposes ;
A receiving circuit to which an output signal of the receiving antenna is input;
A demodulation circuit for demodulating a desired reception signal output from the reception circuit;
A modulation circuit for modulating the demodulated signal output by the demodulation circuit;
The modulated signal output by the modulation circuit, a transmission circuit for transmitting the receiving signal having the same frequency of the reception antennas,
A transmission antenna for transmitting the output signal of the transmission circuit as a radio wave;
A cancel signal adjustment circuit that adjusts the phase and amplitude of the modulation signal and the delay, and outputs a wraparound cancel signal for canceling the transmission signal from the transmission antenna received by the reception antenna;
An adder circuit that adds the wraparound cancel signal output by the cancel signal adjustment circuit to the reception signal output by the receiver circuit to form a desired reception signal demodulated by the demodulation circuit;
A regenerative repeater comprising: a delay circuit that delays the timing of the modulation symbol of the desired reception signal so that the timing phase of the modulation symbol of the desired reception signal and the wraparound cancel signal is the same.   The regenerative repeater according to claim 1, wherein the delay circuit is configured by a low-pass filter or a band-pass filter having a predetermined delay time.   The regenerative repeater according to claim 1, wherein the delay circuit is provided on an output side of the modulation circuit.   4. The regenerative repeater according to claim 1, wherein the modulation circuit is constituted by a digital circuit, and the delay circuit is constituted by a shift register for delaying a modulation signal expressed by a digital numerical value output from the modulation circuit. .   The regenerative repeater according to claim 1, wherein the delay circuit is constituted by a digital circuit and is provided on an output side of the demodulation circuit. The time for which the delay circuit delays the timing of the modulation symbol of the desired reception signal is the desired signal and the undesired signal that appear by a complex correlation operation between the received signal including the desired signal and the undesired signal and the transmission signal. 2. The regenerative repeater according to claim 1, wherein the regenerative repeater is set from a time difference between two peaks corresponding to each of the two .   The reproduction circuit according to claim 1, wherein the delay circuit is provided on a clock supply line for supplying a clock for generating a modulation signal to the modulation circuit, and delays the modulation signal by delaying the clock. Relay device.

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